linux-kernel - Re: C aggregate passing (Rust kernel policy)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAFJgqgRxvUqvgC30Y_n2jOppUH47r=heSYpJb7FiMyw4miW4=w@mail.gmail.com>
Date: Thu, 6 Mar 2025 12:16:00 -0700
From: Ventura Jack <venturajack85@...il.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Kent Overstreet <kent.overstreet@...ux.dev>, Martin Uecker <uecker@...raz.at>, 
	Ralf Jung <post@...fj.de>, "Paul E. McKenney" <paulmck@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
	Gary Guo <gary@...yguo.net>, airlied@...il.com, boqun.feng@...il.com, 
	david.laight.linux@...il.com, ej@...i.de, gregkh@...uxfoundation.org, 
	hch@...radead.org, hpa@...or.com, ksummit@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, miguel.ojeda.sandonis@...il.com, 
	rust-for-linux@...r.kernel.org
Subject: Re: C aggregate passing (Rust kernel policy)

On Wed, Feb 26, 2025 at 4:17 PM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> On Wed, 26 Feb 2025 at 14:27, Kent Overstreet <kent.overstreet@...ux.dev> wrote:
> >
> > This is another one that's entirely eliminated due to W^X references.
>
> Are you saying rust cannot have global flags?
>
> That seems unlikely. And broken if so.
>
> > IOW: if you're writing code where rematerializing reads is even a
> > _concern_ in Rust, then you had to drop to unsafe {} to do it - and your
> > code is broken, and yes it will have UB.
>
> If you need to drop to unsafe mode just to read a global flag that may
> be set concurrently, you're doing something wrong as a language
> designer.
>
> And if your language then rematerializes reads, the language is shit.
>
> Really.
>
>              Linus

Rust does allow global mutable flags, but some kinds of
them are very heavily discouraged, even in unsafe Rust.

    https://doc.rust-lang.org/edition-guide/rust-2024/static-mut-references.html

Best, VJ.